Characterizing low-frequency qubit noise

Abstract

Fluctuations of the qubit frequencies are one of the major problems to overcome on the way to scalable quantum computers. Of particular importance are fluctuations with the correlation time that exceeds the decoherence time due to decay and dephasing by fast processes. The statistics of the fluctuations can be characterized by measuring the correlators of the outcomes of periodically repeated Ramsey measurements. This work suggests a method that allows describing qubit dynamics during repeated measurements in the presence of evolving noise. It made it possible, in particular, to evaluate the two-time correlator for the noise from two-level systems and obtain two- and three-time correlators for a Gaussian noise. The explicit expressions for the correlators are compared with simulations. A significant difference of the three-time correlators for the noise from two-level systems and for a Gaussian noise is demonstrated. Strong broadening of the distribution of the outcomes of Ramsey measurements, with a possible fine structure, is found for the data acquisition time comparable to the noise correlation time.

References in corpus (10)

• Dynamical decoupling and noise spectroscopy with a superconducting flux qubit
• Correlated Charge Noise and Relaxation Errors in Superconducting Qubits
• 1/f Flux Noise in Josephson Phase Qubits
• Low-frequency noise as a source of dephasing of a qubit
• Decoherence in qubits due to low-frequency noise
• Observation of classical-quantum crossover of 1/f flux noise and its paramagnetic temperature dependence
• Multiqubit Spectroscopy of Gaussian Quantum Noise
• A General Transfer-Function Approach to Noise Filtering in Open-Loop Quantum Control
• Noise Spectroscopy Using Correlations of Single-Shot Qubit Readout
• High-Order Qubit Dephasing at Sweet Spots by Non-Gaussian Fluctuators: Symmetry Breaking and Floquet Protection

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• Coherent interaction-free detection of noise
• Enhancing Scalability of Quantum Eigenvalue Transformation of Unitary Matrices for Ground State Preparation through Adaptive Finer Filtering
• Efficient learning and optimizing non-Gaussian correlated noise in digitally controlled qubit systems
• Iterative Adaptive Spectroscopy of Short Signals